The state-of-art mass spectrometry for the analysis of macromolecular ions as proteins, polypeptides and DNA fragments has a major limitation: commercial detectors, based on an ion-electron conversion process in silica, have a strongly decreasing detection probability with decreasing velocity and thus with increasing mass. It is the aim of this proposal to investigate the use of novel Lithium and Cesium based material for fabrication of high efficiency large ion detectors, either by ion-electron or by ion-H-conversion. The new generation of field emissive semiconductor materials is highly promising in this respect. A test assembly will be designed and used to screen and optimize field emissive materials synthesized in our laboratory (or in that of our collaborators) for their electron and H- yields under high mass ion impact. We will measure and compare the detection probabilities of our new materials with those of standard detectors. The complied data will be used for the fabrication of novel detectors to be integrated in our TOF-MS instrumentation. PROPOSED COMMERCIAL APPLICATIONS: We will develop superior ion detectors for large bioions and integrate them into our existing product line for Time-of-Flight instrumentation.